The aim of this project is to increase our understanding of the adaptive mechanisms responsible for maintaining appropriate performance of the vestibulo-ocular reflex. Our previous work had used various optical devices that disturb the visual inputs associated with head movements to show that the gain and the phase of this reflex are both subject to visually-mediated regulation. The present project used 2x telescopic spectacles and fixed-field goggles in conjunction with passive sinusoidal oscillations to adapt the vestibulo-ocular reflex in four rhesus monkeys. Large changes in gain were seen at the adapting frequency, while at adjacent frequencies gain changes were less pronounced and associated with small but highly consistent amounts of phase lag or phase lead. Such frequency selective effects suggest the existence of temporal frequency channels in vestibulo-ocular pathways that are differentiated on the basis of phase shift.